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Physics · Glossary

What is Harmonics?

Also known as: fundamental · harmonic · pure tone

Definition 21.13 High School Physics · Chapter 21 — Sound and Acoustics

A periodic sound of frequency f1f_1 — the fundamental — is in general a sum of sines at the frequencies fn=nf1f_n = n f_1, n=1,2,3,…n = 1, 2, 3, \dots, its harmonics. A sound reduced to its fundamental is a pure tone, like a tuning fork’s.

Examples

Example 21.15 (Why you recognize the caller)

A flute’s A is nearly a pure tone; a violin bowing the same 220 Hz220\,\mathrm{Hz} adds strong harmonics at 440 Hz, 660 Hz and 880 Hz440\,\mathrm{Hz}\text{, }660\,\mathrm{Hz}\text{ and }880\,\mathrm{Hz}. Same pitch and loudness, yet no one confuses them: a voice, too, is a spectrum you know by heart.

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